Drill Bit Cutter Element with Protruding Pilot Portion

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Solution Overview

Problem

Conventional earth-boring drill bits face challenges in maintaining a high rate of penetration and durability when drilling through hard and abrasive formations, leading to frequent bit replacements and increased drilling costs due to the wear and breakage of chisel-shaped inserts.

Innovation Solution

The design incorporates a cutter element with a chisel crest and a pilot portion that extends beyond the chisel crest, featuring a peaked ridge and flanking surfaces, which initiates formation fracture and enhances durability by varying the geometry and orientation of the cutter elements, allowing for better resistance to wear and increased rate of penetration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If chisel-shaped inserts are used to increase rate of penetration in hard formations, then productivity improves, but reliability deteriorates due to wear and breakage

Engineering Contradiction:

Improverate of penetrationVSAvoiddurability of cutter elements

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The cutter element is divided into two distinct functional portions: a pilot portion with a rounded apex for initial fracture and a chisel crest for material removal. This segmentation allows each portion to be optimized for its specific function, with the pilot portion protecting the harder chisel crest from direct impact loads that would cause breakage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the cutter element have different geometric properties: the pilot portion has a rounded apex suitable for initiating fractures in hard formations, while the chisel crest has a sharp peaked ridge for efficient material removal. This local differentiation of properties optimizes both penetration rate and durability.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If conventional cutter element geometry is used, then manufacturing is simple, but productivity decreases due to frequent bit replacements

Engineering Contradiction:

Improvecutter element fabricationVSAvoiddrilling efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The pilot portion performs preliminary fracture of the formation ahead of the chisel crest, pre-conditioning the material to be more easily removed by the chisel portion. This preliminary action increases overall productivity without significantly complicating the manufacturing process.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If cutter elements are designed for durability, then reliability improves, but rate of penetration decreases

Engineering Contradiction:

Improvecutter element lifespanVSAvoidrate of penetration

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

By segmenting the cutter element into pilot and chisel portions, the design achieves both durability (through the protective pilot portion) and high rate of penetration (through the aggressive chisel crest), resolving the trade-off between these two parameters.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design improves the drill bit's ability to maintain a high rate of penetration and durability, reducing the need for frequent replacements and lowering drilling costs by effectively handling hard and abrasive formations.

Implementation Method 1

The pilot portion, with its greater extension height and smaller cross-sectional area, initiates formation fracture, causing cracks to propagate into the uncut formation.

Methodology Applied

Scientific EffectStress concentration and fracture propagation: Fracture Mechanics

Implementation Method 2

The cone cutters roll and slide upon the bottom of the borehole as the bit is rotated, the cone cutters thereby engaging and disintegrating the formation material in its path. The earth disintegrating action of the rolling cone cutters is enhanced by providing the cone cutters with a plurality of cutter elements... the cutter elements on the rotating cone cutters break up the formation to form new boreholes by a combination of gouging and scraping or chipping and crushing.

Methodology Applied

Scientific EffectMechanical crushing and chipping: Impact Force

Implementation Method 3

chips of formation material which are carried upward and out of the borehole by drilling fluid which is pumped downwardly through the drill pipe and out of the bit

Methodology Applied

Scientific EffectFluid transport of cuttings: Fluid Spray

Data Source

PatentUS7631709B2Drill bit and cutter element having chisel crest with protruding pilot portion

Publication Date: 2009.12.15 SMITH INTERNATIONAL INC

AI summary

A rolling cone drill bit includes a cutter element having a cutting portion with a chisel crest and a pilot portion extending beyond the chisel crest. The pilot portion includes a cutting surface that may be generally conical, or form a second chisel crest. The cutting tip of the pilot portion is supported by buttress portions which emerge from and extend beyond the flanks of the chisel crest to provide additional strength and support for the material of the pilot portion that extends beyond the height of the chisel crest.